Browsing by Author "Gerrits, Tim"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Astray: A Performance-Portable Geodesic Ray Tracer
    (The Eurographics Association, 2022) Demiralp, Ali Can; Krüger, Marcel; Chao, Chu; Kuhlen, Torsten W.; Gerrits, Tim; Bender, Jan; Botsch, Mario; Keim, Daniel A.
    Geodesic ray tracing is the numerical method to compute the motion of matter and radiation in spacetime. It enables visualization of the geometry of spacetime and is an important tool to study the gravitational fields in the presence of astrophysical phenomena such as black holes. Although the method is largely established, solving the geodesic equation remains a computationally demanding task. In this work, we present Astray; a high-performance geodesic ray tracing library capable of running on a single or a cluster of computers equipped with compute or graphics processing units. The library is able to visualize any spacetime given its metric tensor and contains optimized implementations of a wide range of spacetimes, including commonly studied ones such as Schwarzschild and Kerr. The performance of the library is evaluated on standard consumer hardware as well as a compute cluster through strong and weak scaling benchmarks. The results indicate that the system is capable of reaching interactive frame rates with increasing use of high-performance computing resources. We further introduce a user interface capable of remote rendering on a cluster for interactive visualization of spacetimes.
  • Thumbnail Image
    Item
    Leveraging BC6H Texture Compression and Filtering for Efficient Vector Field Visualization
    (The Eurographics Association, 2023) Oehrl, Simon; Milke, Jan Frieder; Koenen, Jens; Kuhlen, Torsten W.; Gerrits, Tim; Guthe, Michael; Grosch, Thorsten
    The steady advance of compute hardware is accompanied by an ever-steeper amount of data to be processed for visualization. Limited memory bandwidth provides a significant bottleneck to the runtime performance of visualization algorithms while limited video memory requires complex out-of-core loading techniques for rendering large datasets. Data compression methods aim to overcome these limitations, potentially at the cost of information loss. This work presents an approach to the compression of large data for flow visualization using the BC6H texture compression format natively supported, and therefore effortlessly leverageable, on modern GPUs. We assess the performance and accuracy of BC6H for compression of steady and unsteady vector fields and investigate its applicability to particle advection. The results indicate an improvement in memory utilization as well as runtime performance, at a cost of moderate loss in precision.
  • Thumbnail Image
    Item
    Studying the Effect of Tissue Properties on Radiofrequency Ablation by Visual Simulation Ensemble Analysis
    (The Eurographics Association, 2022) Heimes, Karl; Evers, Marina; Gerrits, Tim; Gyawali, Sandeep; Sinden, David; Preusser, Tobias; Linsen, Lars; Renata G. Raidou; Björn Sommer; Torsten W. Kuhlen; Michael Krone; Thomas Schultz; Hsiang-Yun Wu
    Radiofrequency ablation is a minimally invasive, needle-based medical treatment to ablate tumors by heating due to absorption of radiofrequency electromagnetic waves. To ensure the complete target volume is destroyed, radiofrequency ablation simulations are required for treatment planning. However, the choice of tissue properties used as parameters during simulation induce a high uncertainty, as the tissue properties are strongly patient-dependent. To capture this uncertainty, a simulation ensemble can be created. Understanding the dependency of the simulation outcome on the input parameters helps to create improved simulation ensembles by focusing on the main sources of uncertainty and, thus, reducing computation costs. We present an interactive visual analysis tool for radiofrequency ablation simulation ensembles to target this objective. Spatial 2D and 3D visualizations allow for the comparison of ablation results of individual simulation runs and for the quantification of differences. Simulation runs can be interactively selected based on a parallel coordinates visualization of the parameter space. A 3D parameter space visualization allows for the analysis of the ablation outcome when altering a selected tissue property for the three tissue types involved in the ablation process. We discuss our approach with domain experts working on the development of new simulation models and demonstrate the usefulness of our approach for analyzing the influence of different tissue properties on radiofrequency ablations.
  • Thumbnail Image
    Item
    Towards Glyphs for Uncertain Symmetric Second-Order Tensors
    (The Eurographics Association and John Wiley & Sons Ltd., 2019) Gerrits, Tim; Rössl, Christian; Theisel, Holger; Gleicher, Michael and Viola, Ivan and Leitte, Heike
    Measured data often incorporates some amount of uncertainty, which is generally modeled as a distribution of possible samples. In this paper, we consider second-order symmetric tensors with uncertainty. In the 3D case, this means the tensor data consists of 6 coefficients - uncertainty, however, is encoded by 21 coefficients assuming a multivariate Gaussian distribution as model. The high dimension makes the direct visualization of tensor data with uncertainty a difficult problem, which was until now unsolved. The contribution of this paper consists in the design of glyphs for uncertain second-order symmetric tensors in 2D and 3D. The construction consists of a standard glyph for the mean tensor that is augmented by a scalar field that represents uncertainty. We show that this scalar field and therefore the displayed glyph encode the uncertainty comprehensively, i.e., there exists a bijective map between the glyph and the parameters of the distribution. Our approach can extend several classes of existing glyphs for symmetric tensors to additionally encode uncertainty and therefore provides a possible foundation for further uncertain tensor glyph design. For demonstration, we choose the well-known superquadric glyphs, and we show that the uncertainty visualization satisfies all their design constraints.